Glower for electric lamps.



NlTED ST TES ATENT FFICE.

IALTHER NERNST, 'OF GUTTINGEN, GERMANY, ASSIGNOR TO GEORGE WESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

GLOWER FOR ELECTRIC LAMPS.

srscrrrcarron forming part of Letters Patent No. 685,733, dated October 29, 1901.

Application filed November 8, 1900- To allwhom it may concern.- Be it known that I, WALTHER NERNST, a subject of the Emperor of Germany, and a resident of Gottingen, Empire of Germany, have invented certain new and useful Improvements in Glowers for Electric Lamps, of which the following is a specification. In the operation of electric lamps of the class in which glowers are formed of materialswhich are practically non-conductors when cold and require to be heated to be ren- 'dered conductive it is desirablethat the glowers shall becapable of being operated for a considerable period of time with but little change in the voltage required to cause a given current to pass through them and that they shall vary as little as possible in the amount of. light which they emit during their.

' period of operation, also that they shall have mechanical strength sufiicient to withstand ordinary usage. I have experimented with many different substances which increase in conductivity as they become heated, and I have subjected them to a great variety of tests and have used them for actual lighting purposes during many hours of service. I have made glovvers'- consisting principally of the oxid of. zirconium and having combined or mixed therewith varying percentages of all of the rare earths commonly found in the socalled yttrium group and, in fact, with various other of the rare earths,and I find that excellentglowers may be made by combining or mixing from seventy per cent. to ninety per cent. of zirconia with any or all of the rare earths of the yttrium group in such proportions as they occur in any mineral containing any or all of them. I find,- for instance, that if I combine with zirconia such of the yttrium earths as are found in any mineral containing any or all of them in the proportions of from ninety per cent. to seventy per cent. of zirconia and from ten per cent. to thirty per cent. of the others in their natural proportions a mixture is made from which I an] able to produce glowers having most or all of the qualities desired. In some cases I find it desirable to separate therare Serial No. 85,853. (No specimens.)

and the other containing those belonging to the yttrium group, and to make use of the yttrium group, omitting the cerium group;

but this livision is not always necessary.

The manner in which I make aglower having the constituent elements above referred to is to take the desired percentage of oxid big thateriaL-as, for-instance; tragacanth,

'dextri'ne, or. the like. The powdered oxids are first thoroughly mixed together, and the binding material maybe also finely powdered and thoroughly mixedwith the oxide. Sutficient water is added to form a paste, and the glowers are then shaped by any desired process. The metals ordinarily regarded as belonging'to the yttrium group are yttrium, erbium, terbium, ytterbium, scandium, and such metals as thulium, holmium, dysprosi um, gadolinium, and decipium, which latter are by some chemists ascribed to the yttrium group. The cerium group comprises cerium,

didymium, samarium, and'some others of hypothetical existence. The metals of the cerium group may sometimes be present in the mixture without inconvenience; but new ally they tend to somewhat lower the temper ature at which the glower may be safely operated. This method of preparing glowers or the mixtures from which the glowers are to be, made greatly facilitates the process, for

it simplifies the-process of preparing and refining the materials, as practically it is quite difficult to separate certain of the difierent rare earths from each other, so that it is only necessary to refine the minerals by separating out from them the materials other than the metals of the yttrium group. -The past is pressed or molded into the desired shapes ing brought to a high temperature by heat suitably applied. Terminal conductors are attached in any convenient manner.

I claim as my invention- 1. A glower for electric lamps composed of approximately eighty parts of the oxid of ziror forms and properly dried and baked, be-' I the rare earths of the yttrium group as are contained in yttrium-containing minerals in approximately the proportions that such earths are found therein.

Signed at Berlin, in the Empire of Germany, this 23d day of October, A. D. 1900.

VVALTHER NERNST.

Witnesses:

VVOLDEMAR HAUP'I, HENRY. HASPER. 

